# gpt-oss-20b vs Kimi K2.5

> Kimi K2.5 is the stronger model overall, scoring 47.8 to 32.1 on the Noometry Index. gpt-oss-20b costs 25× less per token, which makes it the better buy when Kimi K2.5's lead doesn't matter for your workload.

- Canonical page: https://noometry.com/compare/gpt-oss-20b-vs-kimi-k2-5
- Last updated: 2026-10-10
- Shared benchmarks: 27

## Summary

- They share 27 benchmarks with published results for both. gpt-oss-20b scores higher in 0 categories and Kimi K2.5 in 9 categories; 9 gaps are clear of the uncertainty.
- The widest gap is in writing & preference, where Kimi K2.5 leads 65.3 to 35.8.
- The biggest single-benchmark swing is Terminal-Bench: 3.4% for gpt-oss-20b and 43.2% for Kimi K2.5.
- gpt-oss-20b is cheaper at $0.018 / $0.09 per million input/output tokens, against $0.45 / $2.25 for Kimi K2.5.
- Kimi K2.5 accepts more context: 262K tokens versus 131K.

## Snapshot

| | gpt-oss-20b | Kimi K2.5 |
|---|---|---|
| Provider | OpenAI | Moonshot AI |
| Noometry Index | 32.1 | 47.8 |
| Rank | 249 | 50 |
| Context | 131K | 262K |
| Input $/M | $0.018 | $0.45 |
| Output $/M | $0.09 | $2.25 |
| Weights | Open | Open |

## Coding

- gpt-oss-20b: 37.1 (#185)
- Kimi K2.5: 48.7 (#48)

| Benchmark | gpt-oss-20b | Kimi K2.5 |
|---|---|---|
| SciCode | 34.4% | 49% |
| WeirdML | 40.9% | 45.6% |
| LMArena Coding | 1307 | 1474 |
| ALE-Bench | 566.05 | 821.65 |
| SWE-bench Verified | — | 73.8% |
| SWE-bench Verified (bash only) | — | 70.8% |
| LMArena WebDev | — | 1436 |
| SWE-bench Multilingual | — | 67.3% |

## Agentic & Tool Use

- gpt-oss-20b: 9.2 (#146)
- Kimi K2.5: 34.0 (#44)

| Benchmark | gpt-oss-20b | Kimi K2.5 |
|---|---|---|
| Terminal-Bench | 3.4% | 43.2% |
| OSWorld | — | 63.3% |
| Vending-Bench 2 | — | 1,198 |

## Reasoning

- gpt-oss-20b: 18.8 (#251)
- Kimi K2.5: 31.2 (#74)

| Benchmark | gpt-oss-20b | Kimi K2.5 |
|---|---|---|
| Kagi LLM Benchmark | 53.2% | 78.5% |
| CritPt | 1.4% | 3.1% |
| Chess Puzzles | 4% | 12% |
| LMArena Hard Prompts | 1274 | 1454 |
| Epoch Capabilities Index | 137.81 | 148.05 |
| ARC-AGI-2 | — | 11.8% |
| SimpleBench | — | 46.8% |
| NYT Connections (extended) | — | 69.9% |
| ARC-AGI-1 | — | 65.3% |
| EnigmaEval | — | 3.4% |
| Thematic Generalization | — | 69.4% |
| DTBench | 68% | — |
| LMCA | 14.5% | — |

## Math

- gpt-oss-20b: 37.6 (#93)
- Kimi K2.5: 50.3 (#46)

| Benchmark | gpt-oss-20b | Kimi K2.5 |
|---|---|---|
| OTIS Mock AIME 2024-2025 | 65.3% | 92.2% |
| LMArena Math | 1317 | 1470 |
| MathArena Final-Answer Competitions | — | 62.3% |
| Omni-MATH | 56.5% | — |
| FrontierMath (Feb 2025 set) | — | 27.9% |
| FrontierMath Tier 4 (v1) | — | 4.2% |

## Knowledge

- gpt-oss-20b: 34.6 (#186)
- Kimi K2.5: 53.6 (#52)

| Benchmark | gpt-oss-20b | Kimi K2.5 |
|---|---|---|
| GPQA Diamond | 60.8% | 87.6% |
| LMArena Expert | 1258 | 1466 |
| Humanity's Last Exam | — | 24.4% |
| SimpleQA Verified | — | 34.3% |
| MMLU-Pro | 74% | — |
| Vectara Hallucination Rate | — | 14.2% |
| GPQA (HELM) | 59.4% | — |

## Multimodal

- gpt-oss-20b: —
- Kimi K2.5: 40.4 (#37)

| Benchmark | gpt-oss-20b | Kimi K2.5 |
|---|---|---|
| LMArena Vision | — | 1269 |
| LMArena Document | — | 1430 |

## Multilingual

- gpt-oss-20b: 42.4 (#192)
- Kimi K2.5: 54.1 (#50)

| Benchmark | gpt-oss-20b | Kimi K2.5 |
|---|---|---|
| LMArena Non-English | 1269 | 1433 |
| LMArena Chinese | 1311 | 1495 |
| LMArena German | 1249 | 1441 |
| LMArena Japanese | 1245 | 1422 |
| LMArena Korean | 1239 | 1412 |
| LMArena Russian | 1279 | 1436 |
| LMArena Spanish | 1267 | 1450 |
| LMArena French | — | 1454 |

## Instruction Following

- gpt-oss-20b: 62.0 (#235)
- Kimi K2.5: 75.5 (#60)

| Benchmark | gpt-oss-20b | Kimi K2.5 |
|---|---|---|
| LMArena Instruction Following | 1236 | 1431 |
| IFEval | 73.2% | — |

## Long Context

- gpt-oss-20b: 37.9 (#203)
- Kimi K2.5: 52.1 (#7)

| Benchmark | gpt-oss-20b | Kimi K2.5 |
|---|---|---|
| LMArena Longer Query | 1251 | 1445 |
| Fiction.LiveBench | — | 86.1% |
| CL-bench | — | 19.3% |
| CL-bench Life | — | 13.2% |

## Writing & Preference

- gpt-oss-20b: 35.8 (#260)
- Kimi K2.5: 65.3 (#51)

| Benchmark | gpt-oss-20b | Kimi K2.5 |
|---|---|---|
| LMArena Text | 1288 | 1445 |
| LMArena Creative Writing | 1201 | 1423 |
| EQ-Bench Creative Writing | 666 | 1579 |
| LMArena Multi-Turn | 1268 | 1444 |
| WildBench | 73.7% | — |

## FAQ

### Is gpt-oss-20b better than Kimi K2.5?

Kimi K2.5 is the stronger model overall, scoring 47.8 to 32.1 on the Noometry Index. gpt-oss-20b costs 25× less per token, which makes it the better buy when Kimi K2.5's lead doesn't matter for your workload.

### Which is cheaper, gpt-oss-20b or Kimi K2.5?

gpt-oss-20b is cheaper. It lists at $0.018 per million input tokens and $0.09 per million output tokens; Kimi K2.5 lists at $0.45 and $2.25.

### Is gpt-oss-20b or Kimi K2.5 better for coding?

Kimi K2.5 scores higher on coding benchmarks: 48.7 versus 37.1 in the Noometry coding category.

### Which has the bigger context window?

Kimi K2.5 does, with 262K tokens against 131K.

### How many benchmarks do gpt-oss-20b and Kimi K2.5 share?

27 benchmarks have published results for both models. gpt-oss-20b has 34 scored results on Noometry and Kimi K2.5 has 51.